Feeding mechanism for sewing machines



.JQ D, KARLE4 2,330,177

FEEDING MECHANISM FOR SEWING MACHINES Filed oct. 25, 1941 I 2sheets-sheet 1 3mm fo/'m D. Kode Sept. 21, 1943. J. D. KARLE FEEDINGMECHANISM FOR SEWING MACHINES 2 Sheets-Sheet 2 Filed Oct. 25, 1941Patented Sept. 21, 1943 s rename ME CHANISM ron snwiNG MACHINES e John-D1. Karle, Rcseile` Park, YJ., assignor to The Singer. ManufacturingVCompany,

Elizabeth, N. J., a corporation of New Jersey Applicatien- October `25,1941, SeriaiNo. 416,437

5 Claims.

1 This invention relates to sewing machines'and more particularly to a`feedingA mechanism lthere- (Cl.V 112-215) sition vwhile it is feedingthe'work so that all of the feed-dog teeth will uniformly feed the work.y

With the above and other objects in View, as will hereinafterappear, theinvention comprises the arrangements of parts hereinafter set forth andillustrated in the accompanyingdrawings of a preferred embodiment of theinvention, from which the several features of the invention and theadvantages attained thereby'will be readily understood by thoseskilledinthe art.

In the accompanying drawings, Fig. 1 isa side elevation, partly insection, of a sewing machine having my improved feeding mechanismembodied therein.

Fig. `2 is a bottomAV plan-view to 'disclose the mechanism beneath thebed.

Fig. 3 isy an endelevation of the machine looking from the left of Fig.1.

Fig. 4 is a diagrammatic view of the feedactuating eccentrics disclosingtheir phase relation.

Fig. 5 is an enlarged fragmentary view of the feed-bar.

In the embodiment of the invention selected for illustration, Ill is thesewing machine bed to which is secured the overhanging frame orgooseneck II which terminates in a hollow head I2. Journaled in thespaced bearings I3 and I4 in the frame I I is a needle-bar and feeddriving-shaft I5 having the usual balance-wheel I6 fixed to the rear endthereof. At its forward end, the shaft I5 actuates, through suitablemechanism carried in the hollow-head I2, a reciprocatory needle-bar Ilwhich carries, at its lower end, an eye-pointed needle I8. Also carriedin the hollow-head I2 is the usual springpressed presser-bar I9 to thelower-end of which is secured, as by a clamp-screw 20, the upright shankZI of the hinged presser-foot 22.

Journaled in bearings 23 and 24 carried by the bed I is the usual rotaryhook-actuating shaft 25. To the forward end of the shaft 25 is securedthe usual hook element 26 which is complemental to the needle I8 in theformation of stitches. This bottom shaft 25 is driven from the top shaftI through the upright shaft 26 which is journaled in the bearing lugs 21and 28 cast in the frame Il. The top shaft I5 has fixed yto it 'a bevelgear 29 which mesheswith a bevel gear 30 xed to'thetop end of theupright shaft 26. The bottom shaft 2-5 carries a bevel gear 3i whichmeshes with a bevel gear 32 fixed to the lower endof the upright shaft2'6. v j

The top-shaft I5 carries the usual work-feeding eccentrics 33 and :34,which actuate the usual pitman rods 35V and36 connected respectively tothe rock-shafts 31 and 3B. Rock-shaft 38y imparts the rising and fallingmovements androck-shaft 3%l`imparts the feed-advance and -returnmovements to thev feed-dog which will hereinafter be described. For amore detailed description of the present feed eccentrics andthepitman'con-A nections reference may be Ahad to Patent Nol 2,161,579, toKaier, dated June 6, 1939.

Secured to one end of' the rock-shaft 3l is a feed-rocker A33 which is frocked back-and-ferth by thepitman 35. Oneendof a feed-baum;I carrying a'feeddog 4I is pivotally` connectedto this feed-rocker 39 and its otherend is formedas a fork 42 which is provided with an arcuately shapedslot 43. -Slidingly engagingthe slot43-a're V the broad bearing surfacesof a ccrrespondingly arcuately shaped wear-block 44 which is pivotallymounted upon the pin 45 carried by the feed-lift crank 46. Thisfeed-lift crank 46 is fixed to the rock-shaft 33 which oscillates thecrank up and down and thereby imparts rising and falling movements tothe feed-dog 4 I.

The feed-actuating eccentrics 34 and 35 are disposed relative to eachother so that they are substantially out of phase. This phase relationof the eccentrics will effect a timed relation between therising-and-falling and backwardand-forward movements of the feed-bar,and consequently of the feed-dog, such as are common to so-calledfour-motioned feeding mechanisms.

In this type of feeding mechanism it is desirable to have the feed-dogfeeding surface parallel to the sewing machine working surface while thefeed-dog is in contact with the work advanced thereby. I-Ieretofore, Vinsewing machines using the present type of four-motioned feedingmechanisms having the usual feed-rocker and feed-lift crank, thefeed-dog begins to drop when the feed-lift eccentric has passed throughits uppermost dead center position. At this time the feed-dog is movingfrom front to rear in its work feeding stroke. To counteract thiscondition in the present construction, I have provided in the feed-barfork 42, a slot 43 having side-walls formed as the arcs of twoconcentric circles. As may be seen in Figs. 3 and 5, the slot 43 iscurved downwardly towards the feed-lift crank 46, and the center ofcurvature C of the slot 43 lies at a. level below the feed-bar 4U, asindicated in Fig. 5.

It is the function of the arcuately shaped slot 43 to eieot anaccelerated rising movement in the fork 42, relative to the feed-liftcrank`46, as the feed-advance rocker 39 moves the feed-bar 40 from frontto rear. It is this rising movement of the fork 42, relative to thecrank 46, that compensates for the accelerated drop of the crank 46 andthus maintains a substantially parallel relation between the feedingsurface of the feeddog 4| and the machine working surface for aprolonged portion of the feed-stroke of the feeddog 4 I. In the presentillustrated sewing machine the working surface level is represented bythe top of the throat-plate 41.

Having thus set forth the nature of the invention what I claim hereinis:

1. A work-feeding mechanism for sewing machines comprising, a feed-bar,a feed-dog carried by said feed-bar, one end of said feed-bar beingprovided with an arcuate slot, the center of curvature of said slotlying below said feed-bar, means operatively engaging said-arcuate slotfor imparting rising and falling movements to said feed-dog, and meansoperatively connected to the other end of said feed-bar for impartingwork-advancing and -return movements to said feed-dog.

2. A feeding mechanism for sewing machines comprising, a feed-bar, afeed-dog carried by said feed-bar, means operatively connected to oneend of said feed-bar for imparting work-advancing and -return movementsto said feed-dog, and means including a member having a bearingportionshaped as an arc of a circle slidingly engaging the other end of saidfeed-bar for the purpose cf imparting rising and falling movements tosaid feed-dog, the center of curvature of said arc lying at a pointbelow the level of said feed-bar. l

3. A work-feeding mechanism for sewing machines comprising, a feed-bar,a feed-dog carried by said feed-bar, a fork carried by one end of saidfeed-bar and having an arcuate slot formed therein, an oscillatingcrank, a wearblock pivotally carried by one end of said crank andslidingly engaging said arcuate slot for the 5 purpose of impartingrising `and falling movements to said feed-dog, said slot being inclineddownwardly towards said oscillating crank and having its center ofcurvature disposed at a point below the level of said feed-bar, andmeans operatively connected to the other end of said feedbar forimparting work-advancing and -return movements to said feed-dog.

4. A work-feeding mechanism for sewing machines comprising, afeed-rocker, a feed-bar having one of its ends pivoted to saidfeed-rocker,

a feed-dog carried by said feed-bar, a fork carried by the other end ofsaid feed-bar and having an arcuate slot formed therein, an oscillatingfeed-lift crank, and a block pivotally carried by one end of said crankand slidingly engaging said arcuate slot, said arcuate slot beinginclined downwardly towards said oscillating feed-lift crank and havingits center of curvature disposed at a point below the level of saidfeed-bar.

5. In a sewing machine having a framaa rotatable feed-actuating shaftjournaled in said frame, a pair of eccentrics mounted upon saidfeed-actuating shaft and disposed substantially 90 out of phase relativeto each other, a feed- A rocker carried by said frame and actuated byone of said eccentrics, a feed-bar having one of its ends pvotallyconnected to said feed-rocker, a feed-dog carried by said feed-bar, andan oscillating feed-lift crank actuated by the other eccentric andoperatively engaging the other end of said feed-bar; the improvementwhich consists in the provision in the feed-bar of a fork having anarcuate slot, and an arcuately shaped block pivotalfly carried by saidfeed-lift crank and slidingly engaging said arcuate slot, said arcuateslot being inclined downwardly towards said feedlift crank and havingits center of curvature disposed at a point below the level of saidfeed-bar.

JOHN D.

